Magnetic correlations in Ho{sub x}Tb{sub 2-x}Ti{sub 2}O{sub 7}

Journal Article · Fri Apr 01 00:00:00 EDT 2011 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PHYSREVB.83.144413· OSTI ID:21538278

Chang, L J ^[1]; Schweika, W; Persson, J; Brueckel, Th ^[2]; Kao, Y -J ^[3]; Chou, Y Z ^[3]; Yang, H C ^[3]; Chen, Y Y ^[4]; Gardner, J S ^[5]

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1. Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan (China)
2. Institut fuer Festkoerperforschung, Forschungszentrum Juelich, DE-52425 Juelich (Germany)
3. Department of Physics, National Taiwan University, Taipei 106, Taiwan (China)
4. Institute of Physics, Academia Sinica, Nankang Taipei 115, Taiwan (China)
5. Indiana University, 2401 Milo B. Sampson Lane, Bloomington, Indiana 47408 (United States)

Polycrystalline samples of Ho{sub x}Tb{sub 2-x}Ti{sub 2}O{sub 7} (0 < x < 2) have been prepared and characterized for their structural and magnetic properties. The parent compounds of this solid solution are the spin ice Ho{sub 2}Ti{sub 2}O{sub 7} and the spin liquid Tb{sub 2}Ti{sub 2}O{sub 7}. Specific-heat measurements on HoTbTi{sub 2}O{sub 7} (x = 1.0) reveal the absence of a long-range order state above 0.5 K. The integrated entropies of all Ho{sub x}Tb{sub 2-x}Ti{sub 2}O{sub 7} specimens up to 30 K scale well with the ratio of spin ice and spin liquid in the composition. The neutron diffraction spectrum of HoTbTi{sub 2}O{sub 7} exhibits a dipolar spin-ice pattern and can be well described by mean-field theory for <111> Ising spins, nearest-neighbor exchange, and dipolar interactions. Inelastic neutron scattering on HoTbTi{sub 2}O{sub 7} reveals two dispersionless excitations, one of {approx}2.5 meV out of the ground state, and a 4-meV transition out of an excited state. We argue that these data suggest that the very strong single-ion effects of Ho{sub 2}Ti{sub 2}O{sub 7} and Tb{sub 2}Ti{sub 2}O{sub 7} persist in the Ho{sub x}Tb{sub 2-x}Ti{sub 2}O{sub 7}(0 < x < 2) solid solution, whereas the Tb-Ho correlations are weak, resulting in small shifts in the energy scales but with no dramatic effect on the bulk properties.

• OSTI ID: 21538278
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Vol. 83, Issue 14; Other Information: DOI: 10.1103/PhysRevB.83.144413; (c) 2011 American Institute of Physics; ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CORRELATIONS
CRYSTAL STRUCTURE
ENTROPY
EXCITATION
HOLMIUM COMPOUNDS
INELASTIC SCATTERING
INTERACTIONS
LIQUIDS
MAGNETIC PROPERTIES
MEAN-FIELD THEORY
NEUTRON DIFFRACTION
POLYCRYSTALS
SOLID SOLUTIONS
SPECIFIC HEAT
SPECTRA
SPIN
TERBIUM COMPOUNDS
TITANATES
ANGULAR MOMENTUM
COHERENT SCATTERING
CRYSTALS
DIFFRACTION
DISPERSIONS
ENERGY-LEVEL TRANSITIONS
FLUIDS
HOMOGENEOUS MIXTURES
MIXTURES
OXYGEN COMPOUNDS
PARTICLE PROPERTIES
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
SCATTERING
SOLUTIONS
THERMODYNAMIC PROPERTIES
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS